Louver unit having a fire resistant seal

ABSTRACT

A louver unit which closes to prevent passage of smoke through air ducts, provided with a fire resistant seal that does not deteriorate at high temperatures. The louver unit includes a housing having an opening in which are mounted two blades, at least one of which is movable relative to the other between an open position and a closed position in which the blades overlap. Fixed to and extending along one of the blades is a resilient sealing strip of heat resistant material such as metal. The strip includes a median portion free to flex away from the blade, which extends around the edge of the blade to which it is attached and projects beyond it towards the other blade. Closing motion brings a free lip of the sealing strip into contact with the other blade in advance of contact between the blades themselves. Further motion to the fully closed position of the blades flexes the sealing strip so that the lip is resiliently biased into sealing contact with the other blade.

United States Patent Hess LOUVER UNIT HAVING A FIRE RESISTANT SEAL [75] Inventor: Louis R. Hess, Newport Beach,

Calif.

[73] Assignee: Pacific Air Products Co., Santa Ana,

Calif.

[22] Filed: June 28, 1973 [21] Appl. No.: 374,318

[52] U.S. Cl 98/110, 49/91, 49/92, 137/601 [51] Int. Cl F24f 13/14 [58] Field of Search 49/91, 92; 98/107, 110, 98/112, 113; 160/236; 137/601 [56] References Cited UNITED STATES PATENTS 2,287,262 6/1942 Merry 98/86 3,530,783 9/1970 Alamprese 3,543,439 12/1970 Pantland 49/92 X 3,606,245 9/1971 Rekhow et al 137/601 X 3,698,429 10/1972 Lowe et al. 137/601 Primary Examiner-William F. ODea Assistant Examiner-Peter D. Ferguson Attorney, Agent, or Firm-Fulwider Patton, Rieber, Lee & Utecht [5 7 ABSTRACT A louver unit which closes to prevent passage of smoke through air ducts, provided with a fire resistant seal that does not deteriorate at high temperatures: The louver unit includes a housing having an opening in which are mounted two blades, at least one of which is movable relative to the other between an open position and a closed position in which the blades overlap. Fixed to and extending along one of the blades is a resilient sealing strip of heat resistant material such as metal. The strip includes a median portion free to flex away from the blade, which extends around the edge of the blade to which it is attached and projects beyond it towards the other blade. Closing motion brings a free lip of the sealing strip into contact with the other blade in advance of contact between the blades themselves. Further motion to the fully closed position of the blades flexes the sealing strip so that the lip is resiliently biased into sealing contact with the other blade.

12 Claims, 3 Drawing Figures 1 LOUVER UNIT HAVING A FIRE RESISTANT SEAL BACKGROUND OF THE INVENTION This invention relates to a louver unit having movable blades, which may be installed in a duct such as an air conditioning duct to shut off flow to prevent transmission of smoke in the event of fire. In particular, it relates to a louver unit of such a type wherein a heat resistant resilient seal is provided to prevent flow of smoke between the blades in their closed position.

In buildings provided with air conditioning ductwork, such as office buildings, apartment blocks and the like, fire precautions frequently require that means be provided for closing the ducts in the event of fire to prevent transmission of smoke throughout the building to prevent asphyxiation and other serious hazards. For this purpose, special fire control louver units may be installed in the ductwork at strategic locations. Such fire control louver units commonly include a housing in which are mounted one or more movable metal blades which remain in a permanently, fully open position during the life of the building unless a fire occurs. In the event of fire, the blades are turned through 90 by solenoids connected to heat or smoke responsive sensors which function automatically, to completely close the opening through the unit.

Because louver blades can be quite lengthy, up to 4 feet, for example, and tend to suffer from waviness and other surface irregularities, a plain metal-to-metal contact between the edges of adjacent louver blades in the closed position can leave sufficient gaps for leakage of a dangerously high fraction of the smoke. It has therefore been customary on louver units of this kind to provide resilient compressible sealing material between the cooperating edge surfaces of the louver blades to provide an airtight seal preventing leakage of smoke between the closed blades.

Operational safety problems may, however, arise where compressible sealing materials, those commonly used being felt, neoprene, or silicone rubber, are relied on to create the seal between the louver blades. In an actual fire environment, smoke through the duct is frequently accompanied by air at a very elevated temperature sufficient to cause burning, charring, or at the least, loss of the resilient properties of, the sealing material. As a result, the seal is effectively destroyed and smoke may be able to pass in substantial quantities through the metalto-me tal gaps between the closed louver blades. If this occurs, the safety function of the fire control louver unit is rendered, to a considerable extent, ineffective.

In addition, some compressible seal materials can lose their resilience over the years due to cracking or perishing, with the results that if fire occurs long after the units were installed, the seals may no longer be in suitable condition to effectively prevent leakage of smoke between the louver blades.

SUMMARY OF THE INVENTION A louver unit according to the invention includes at least one resiliently flexible metal sealing strip which is resistant to elevated temperatures and maintains an unimpaired seal about the edges of adjacent closed louver blades. The strip has plural axes of flexure enabling it to flex readily so that it maintains an effective seal despite waviness or irregularity in the blade surface against which it abuts. The metal-to-metal seal provided by the edge of the resilient sealing strip against the adjacent blade, does not deteriorate with increasing temperature in the manner that a seal dependent upon the resilient qualities of compressible material would do. In addition, the resilient metal sealing strips are not subject to spontaneous deterioration in sealing quality over long periods of time, unlike some compressible resilient sealing materials.

The sealing strip includes an anchored portion fixedly secured to the first blade on its side remote from the second blade. A median portion of the sealing strip extends from the anchored ortion and is free to flex away from the adjacent blade. The median portion extends around the first edge and has a free lip which is located beyond the side of the first blade proximate to the second blade. Closing motion of the blades causes contact between the lip of the sealing strip and the second blade in advance of contact between the blades themselves. Further motion to the closed position of the blades flexes the sealing strip thereby resiliently biasing its lip into sealing contact against the second blade.

In the preferred embodiment, the median portion includes an intermediate portion and integral with the anchored portion and inclined in a direction away from the second blade. The juncture between the intermediate portion and the anchored edge portion constitutes a first axis of flexure. Extending from the intermediate portion of the sealing strip toward the second blade, is

an end portion of the strip which terminates in the previously mentioned free lip. The end and intermediate portions of the sealing strip together define a generally L-shaped configuration and their juncture constitutes a second axis of flexure. A third axis of flexure is also provided by bending the lip of the sealing strip at an inclination to the adjacent end portion of the strip. Surface variations or waviness in the surface of the blades are accommodated by flexing of the strip about its three axes of flexure to maintain a seal between the blades along their full lengths.

BRIEF DESCRIPTION OF THE DRAWINGS A louver unit according to the invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a perspective view, partially in crosssection, of a louver unit constructed in accordance with the preferred embodiment of the invention, with two louver blades, forming a part of the invention,'shown in a closed condition;

FIG. 2 is-an enlarged cross-sectional side view of a portion of the louver unit shown in FIG. 1 taken along the lines 22 therein, illustrating a resiliently flexible heat resistant sealing strip, forming a part of the invention; and

FIG. 3 is a cross-sectional view corresponding to FIG. 2 but with the louver blades shown in a partially open condition.

DETAILED DESCRIPTION A louver unit (FIG. 1) is installed for fire control purposes in a building air duct to close the duct in the event of fire and prevent smoke being distributed through the building via .the duct. The unit includes a housing 2 configured as a rectangular frame having a vertical and transversely extending opening through it. The housing 2 is mounted in an air duct 4 and includes upper and lower (or first and second) movable louver blades positioned within and extending across the opening through the housing 2. The louver blades 6 and 8 are of generally rectangular, plate-like configuration and, in the closed position shown in FIG. 1, occupy the entire area of the opening through the housing. The blades are mounted on transversely extending, generally horizontal, upper and lower axles l and 12 which are rotatably mounted in journals in the sidewalls of the housing 2. The lower axle 12 is connected via a crank arm 14 to the output shaft 16 of a solenoid. The solenoid forms part of operating circuitry (not shown) which automatically actuates the solenoid when smoke is detected on the upstream side of the duct.

The louver unit of the present invention is not a regularly controlled unit for variably regulating flow through the duct, but is a two position OPEN-SHUT device operating only in the event of fire to close the duct. Thus, in the absence of fire, the louver blades 6 and 8 remain in a permanent fully open position extending in parallel horizontal relation so that air can pass freely along the duct 4 through the opening in the housing 2. However, in the event of fire, the solenoid operates extending the arm 16 to pivot the arm 14 and rotate the shaft 12. Turning motion of the shaft 12, which moves the lower louver blade 8, is transmitted to the upper louver blade 6 through a parallel arm linkage which insures that the upper and lower louver blades move in unison. The parallel arm linkage includes a lower arm 18 secured to and projecting horizontally from the lower louver blade 8, a parallel upper arm 20 secured to and projecting from the upper louver blade 6, and a vertical link 22 pivotally connected between the extremities of the upper and lower arms 18 and 20 in parallel relation to the surfaces of the upper and lower louver blades. Rotation of the axle I2 is stopped by engagement of the edges of the blades when they reach the closed, vertically aligned position shown in FIG. 1 extending across and closing the opening through the housing 2 to prevent passage of air along the duct 4.

As may be seen from FIG. 2, each of the louver blades is provided with a reversely bent stiffening rib along each of its upper and lower edges. Thus the rib 24 along the lower edge of the upper louver blade 6, is constituted by an intermediate wall 26 of the blade which is bent out of the plane of the remainder of the blade and extends at an inclination away from the opposing, lower blade 8. Extending from the end of the intermediate wall 26 is an end wall 28 reversely bent back through approximately 90 and terminating in the plane of the remainder of the upper blade 6. The rib 24 along the upper edge of the lower blade 8 is of identical but oppositely facing configuration. In the closed position of the louver blades, the two ribs come together to define a generally diamond-shaped enclosure, the blades overlapping each other in the rib region with the extreme edge of each blade abutting the other blade beyond the rib.

Despite this abutting contact between the blades, substantial quantities of smoke might still be able to pass between the closed blades through gaps between them arising from irregularities in their surfaces. It must be appreciated that louver blades in a unit of this kind can be of appreciable length, for example up to 4 feet, and being made out of sheet material are subject to noticeable amounts of waviness and warping along their length which can create local gaps and crevices when the blades are brought together. Gaps can also be created by pits and impact indentations in the sheet material. Such problems are aggravated by the requirements of low cost mass production.

The present invention is particularly directed to structure to provide a seal about the overlapped edges of the adjacent louver blades in the closed position, which maintains its smoke tight nature even at highly elevated temperatures. For this purpose the lower unit includes resilient metal sealing strips 30 fixedly secured to the movable blades. Each sealing strip is arranged to be pressed against the other blade associated with it when the blades are in the closed position and to flex resiliently into tight sealing contact therewith despite substantial surface irregularities in the surface of the other blade against which the strip is pressed. In this manner a seal is maintained even though the temperatures in the duct may rise to very high temperatures which would destroy the sealing qualities of compressible materials, such as neoprene, if they had been used.

In more detail the upper blade 6 is provided with a resilient, strip metal seal 30 extending the full length of its lower edge. The sealing strip in the preferred embodiment is a thin sheet of resilient, stainless steel of generally rectangular strip-like configuration, although other heat resistant materials possessing a springy nature may be utilized. The sealing strip includes an anchored upper portion 32 lying fiat against the surface of the upper blade 6 on its side remote from the other lower blade 8. The anchored portion 32 is fixedly secured to the upper blade by spot welds 33 spaced transversely along its length at suitable intervals, although other methods of attachment such as rivets may be utilized. The sealing strip 30 also includes an offset median portion 34 integral with the anchored portion, free to flex relative to the blade. The median portion 34 extends around the lower edge of the upper blade 6 and terminates in a free lip 36. In an unflexed condition, the lip 36 (FIG. 3) extends beyond the plane of the side of the blade 6 facing towards the other louver blade 8.

The strip 30 has three different fiexure axes. The previously mentioned median portion 34 of the sealing strip includes a first intermediate portion 38 (FIG. 3) extending integrally from the anchored portion 32 at an inclination corresponding generally to the inclination of the intermediate wall 26 of the underlying rib 24 on the blade. The juncture between the anchored portion 32 and the first intermediate portion 38 constitutes a first fiexure axis 39 extending transversely along the length of the sealing strip. The first intermediate portion 38 of the sealing strip terminates in a reversely bent second intermediate portion 40 projecting towards the other louver blade 8 and in general alignment with the wall 28 of the underlying rib 24. The juncture between the first and second intermediate portions 38 and 40 of the sealing strip constitutes a second fiexure axis 42 which also extends transversely along the length of the sealing strip. The previously mentioned lip 36 is bent away from the second intermediate portion 40. The juncture between the portion 40 and the lip 36 constitutes a third fiexure axis 44.

As the blade move into contact, the free edge portion 36 of the sealing strip contacts the lower louver blade 8 in advance of actual contact between the blades themselves. Further closing motion of the blades to the fully closed position flexes the sealing strip so that the lip 36 is resiliently biased against the lower blade providing an effective seal which prevents the passage of smoke through any gaps that may exist between the blades in their closed position. The three different axes of flexure distribute the flexing action of the strip to enable the lip to accommodate surface irregularities and waviness in the second blade and maintain a seal against it. The resilient flexural bias is assisted by a .pressure bias obtained by positioning the sealing strips on the upstream side of the blades (the direction of air flow being indicated by the arrow in FIG. 1).

ln addition to preventing leakage of smoke between the louver blades, it is also necessary to prevent smoke escaping between the louver blades and the upper and lower ends of the housing. For this purpose, the upper end of the housing is provided with a dependent, stationary blade 48 (FIG. 1) extending transversely of the housing along the upstream side of the upper blade. The blades are of reversely symmetrical configuration and the upper end of the upper blade 6 is of the same configuration as the upper end of the lower blade 8 shown in FIG. 2, that is to say having a rib 24 constituted by walls 26 and 28 with the concave side of the rib facing upstream. A seal 50 (FIG. 1), of similar configuration to the sealing strip 30 previously described, but inverted and facing in an upstream direction, is mounted about and embracing the rib 24 on the upper edge of the upper blade 6. The sealing strip 50 has a lip 52, similar to the lip 36 of the sealing strip 30 previously described, which faces towards and engages the stationary blade 48 to form a resiliently biased seal thereagainst when the upper louver blade 6 is in the closed position.

A similar arrangement involving a second stationary louver blade 54 and a further resilient sealing strip 56 (similar to the sealing strip 30) positioned along the lower edge of the lower louver blade 8, prevents leakage of smoke between the lower louver blade and the bottom of the housing 2.

Smoke is also prevented from leaking between the louver blades and the vertical sides of the housing 2. For this purpose, vertically extending, box-like metal diaphragms 60 are mounted between the sidewalls of the housing 2 extending into abutting, sliding contact with the vertical, end edges of the upper and lower louver blades thereby preventing the passage of smoke.

Thus, to summarize, the present invention provides a louver unit for installation in an air duct to prevent passage of smoke in the event of fire, in which heat resistant seals are employed that do not become degraded under the extreme operating temperatures encountered in fires. In particular the use of flexible metal sealing contacts forming a resiliently biased metal-tometal sealing contact with the louver blades and the adjacent stationary blades, avoids the problems of loss of seal quality associated with the use of compressible, heat destructible material seals that can occur at very high temperatures. The resilient seals of the present invention, moreover, do not tend to age, harden or otherwise degrade over extended periods of time thus maintaining their sealing quality even though use may not be required for many years. The quality of the resilient seal obtained is enhanced by the provision of three different flexure axes which enable the seal to conform readily to both minor and major surface irregularities in the louver blades. The structure described can be fabricated at low cost and is also rugged.

Although the invention has been described with reference to a preferred embodiment, it will be appreciated by one skilled in the art, that modifications, deletions, substitutions and other changes may be made which will come within the spirit of the invention.

I claim:

1. A louver unit comprising,

a housing having an opening therethrough,

first and second blades connected with said housing extending across said opening, said first and second blades having adjacent first and second edges, respectively,

means for moving at least one of said blades relative to the other between, an open position in which said first and second edges are spaced apart to permit flow through said opening between said blades, and a closed position in which said blades are in overlapping, abutting contact adjacent said edges to restrict flow through said opening between said blades,

a resilient sealing strip of heat resistant material, said sealing strip including,

an anchored portion fixedly secured to said first blade on a side thereof remote from said second blade, and disposed in side-to-side contact against said first blade,

a median portion free to flex away from said first blade extending from said anchored portion around said first edge, said median portion including a first intermediate portion integral with said anchored portion extending therefrom at an inclination away from said second blade, said first intermediate and anchored portions at their juncture defining a first flexure axis, and a second interme diate portion integral with said first intermediate portion extending therefrom at an inclination towards said second blade, said first and second intermediate portions defining a generally L-shaped configuration, and said first and second intermediate portions at their juncture defining a second axis of flexure, and

a lip connected with said second intermediate portion of said sealing strip and spaced beyond said first blade on a side thereof proximate to said second blade, closing motion of said blades causing contact between said lip and said second blade in advance of contact between said blades, further motion to said closed position causing flexing of said strip about said first and second axes of flexure, thereby resiliently biasing said lip into sealing contact against said second blade.

2. A louver unit as defined in claim 1, wherein said lip is directed at an inclination from said second intermediate portion of said sealing strip away from said first intermediate portion, said lip and said second intermediate portion at their juncture defining a third axis of flexure for said sealing strip, thereby providing improved contact between said sealing strip and said second blade.

3. A louver unit as defined in claim 2, wherein said second blade is stationary relative to said housing and and second axes respectively, said axes extending transversely of said opening.

5. A louver unit as defined in claim 4, wherein said opening in said housing extends in generally vertical and transverse directions and said first and second axes of rotation of said blades are disposed in generally horizontal, vertically spaced relation, said first and second blades in the closed position thereof, extending in generally vertical alignment within said opening.

6. A louver unit as defined in claim 5, further includmg,

means connected with said first and second blades for moving said blades in unison between said open and closed positions.

7. A louver unit as defined in claim 2, wherein said sealing strip is formed of springy sheet metal having a high melting point and retaining its resilient qualities at elevated temperatures.

8. A louver unit as defined in claim 1, further includmg,

a reversely bent rib formed integrally with said first blade extending along and adjacent said first edge, said rib shaped to fit in approximate conformation against at least a portion of the interior surface of said median portion of said sealing strip.

9. In a louver unit having at least one elongated blade having a free longitudinal edge portion movable between open and closed positions, and a closure element for engaging one side of said longitudinal edge portion when the latter is in said closed position, an improved seal comprising:

an elongated strip of resiliently flexible sheet metal extending along said free edge portion of said blade on the side thereof opposite said one side, and having a longitudinal lip projecting outwardly beyond the free edge of said blade and laterally beyond said one side for engagement with said closure element in advance of said one side during movement of said free edge portion into said closed position;

means securing said strip to said opposite side in an area spaced from said free edge and leaving'said strip free to flex between said lip and said securing means, to accommodate surface irregularities in said closure element;

and means enhancing the flexibility of said strip between said securing means and said lip, to distribute flexure of said strip across the width thereof, said means for enhancing the flexibility of said strip comprising a plurality of longitudinal flexure axes.

10. A louver unit as defined in claim 9 in which said flexure axes comprise longitudinal bends which form a median portion in said strip that is offset away from said closure element between said lip and said securing means.

11. A louver unit as defined in claim 9 in which said lip is formed integrally with the remainder of said strip and is joined thereto by a longitudinal bend inclining said lip outwardly and toward said closure member.

12. A louver unit as defined in claim 9 in which said blade has a raised contour adjacent said free edge portion, and said sealing strip is contoured to follow the contour of said blade from said securing means to said free edge, said lip being inclined outwardly and away from said blade adjacent said free edge and extending beyond the latter to be pressed into sealing engagement with said closure element when said free edge portion is in said closed position. 

1. A louver unit comprising, a housing having an opening therethrough, first and second blades connected with said housing extending across said opening, said first and second blades having adjacent first and second edges, respectively, means for moving at least one of said blades relative to the other between, an open position in which said first and second edges are spaced apart to permit flow through said opening between said blades, and a closed position in which said blades are in overlapping, abutting contact adjacent said edges to restrict flow through said opening between said blades, a resilient sealing strip of heat resistant material, said sealing strip including, an anchored portion Fixedly secured to said first blade on a side thereof remote from said second blade, and disposed in side-to-side contact against said first blade, a median portion free to flex away from said first blade extending from said anchored portion around said first edge, said median portion including a first intermediate portion integral with said anchored portion extending therefrom at an inclination away from said second blade, said first intermediate and anchored portions at their juncture defining a first flexure axis, and a second intermediate portion integral with said first intermediate portion extending therefrom at an inclination towards said second blade, said first and second intermediate portions defining a generally L-shaped configuration, and said first and second intermediate portions at their juncture defining a second axis of flexure, and a lip connected with said second intermediate portion of said sealing strip and spaced beyond said first blade on a side thereof proximate to said second blade, closing motion of said blades causing contact between said lip and said second blade in advance of contact between said blades, further motion to said closed position causing flexing of said strip about said first and second axes of flexure, thereby resiliently biasing said lip into sealing contact against said second blade.
 2. A louver unit as defined in claim 1, wherein said lip is directed at an inclination from said second intermediate portion of said sealing strip away from said first intermediate portion, said lip and said second intermediate portion at their juncture defining a third axis of flexure for said sealing strip, thereby providing improved contact between said sealing strip and said second blade.
 3. A louver unit as defined in claim 2, wherein said second blade is stationary relative to said housing and said first blade is movably mounted on said housing.
 4. A louver unit as defined in claim 2, wherein said first and second blades are both connected with said housing for rotational movement about parallel first and second axes respectively, said axes extending transversely of said opening.
 5. A louver unit as defined in claim 4, wherein said opening in said housing extends in generally vertical and transverse directions and said first and second axes of rotation of said blades are disposed in generally horizontal, vertically spaced relation, said first and second blades in the closed position thereof, extending in generally vertical alignment within said opening.
 6. A louver unit as defined in claim 5, further including, means connected with said first and second blades for moving said blades in unison between said open and closed positions.
 7. A louver unit as defined in claim 2, wherein said sealing strip is formed of springy sheet metal having a high melting point and retaining its resilient qualities at elevated temperatures.
 8. A louver unit as defined in claim 1, further including, a reversely bent rib formed integrally with said first blade extending along and adjacent said first edge, said rib shaped to fit in approximate conformation against at least a portion of the interior surface of said median portion of said sealing strip.
 9. In a louver unit having at least one elongated blade having a free longitudinal edge portion movable between open and closed positions, and a closure element for engaging one side of said longitudinal edge portion when the latter is in said closed position, an improved seal comprising: an elongated strip of resiliently flexible sheet metal extending along said free edge portion of said blade on the side thereof opposite said one side, and having a longitudinal lip projecting outwardly beyond the free edge of said blade and laterally beyond said one side for engagement with said closure element in advance of said one side during movement of said free edge portion into said closed position; means securing said strip to said opposite side in an area spaced from said free edGe and leaving said strip free to flex between said lip and said securing means, to accommodate surface irregularities in said closure element; and means enhancing the flexibility of said strip between said securing means and said lip, to distribute flexure of said strip across the width thereof, said means for enhancing the flexibility of said strip comprising a plurality of longitudinal flexure axes.
 10. A louver unit as defined in claim 9 in which said flexure axes comprise longitudinal bends which form a median portion in said strip that is offset away from said closure element between said lip and said securing means.
 11. A louver unit as defined in claim 9 in which said lip is formed integrally with the remainder of said strip and is joined thereto by a longitudinal bend inclining said lip outwardly and toward said closure member.
 12. A louver unit as defined in claim 9 in which said blade has a raised contour adjacent said free edge portion, and said sealing strip is contoured to follow the contour of said blade from said securing means to said free edge, said lip being inclined outwardly and away from said blade adjacent said free edge and extending beyond the latter to be pressed into sealing engagement with said closure element when said free edge portion is in said closed position. 